We propose a five-year program of research aimed at assessing the prevalence and incidence of temporomandibular disorder (TMD) pain, headache, back pain, and abdominal pain in adolescents., and identifying risk factors for onset of each of these common pain {{symptoms}}. Because the prevalence of headache and TMD pain is much higher in adult women than in adult men, the studies are designed to test the global hypothesis that this prevalence differences begin in adolescence and are associated with the hormonal change of puberty. The specific aims of study 1 are: 1) In a telephone survey, assess the prevalence, severity and temporal characteristics of TMD pain, headache, backpain and abdominal pain in an age- and sex-stratified random sample of adolescents, ages 11- 17 (final n= 2970) from a defined population; 2) Identify potential risk factors for pain at each of these four sites; 3) Conduct standardized examinations and interviews for all respondents reporting TMD pain, as well as a sample of those without TMD pain (expected n's = 130 per respondents reporting TMD pain, as well as a sample of those without TMD pain (expected n's = 130 peer group) in order to: a) compare the rates of clinical signs and symptoms of temporomandibular disorders in cases and controls, and b) estimate the prevalence of specific clinical subtypes of TMD (myofascial pain, disc displacements, arthralgia, arthritis/arthrosis) using standardized examination methods and diagnostic algorithms. Examinations will be conducted in subjects' homes by Registered Dental Hygienists training and calibrated for reliability. The specific aims of Study 2 are: 1) Follow the cohort of 11 year old respondents from Study 1 (n= 1902) over a 3-year follow up period, using brief mail-in surveys and more extensive follow up data collection at 18 months and 3 years. Monitor rates of onset of TMD pain, headache, back pain and abdominal pain. Assess the impact of these pain problems in terms of interference with activities, use of medications and rates of health care use for pain; 2) Identify risk factors for onset of {{TMD pain, headache, back and abdominal pain}}> Hypothesized risk factors for all pains include: female gender, number of existing pain complaints, and other somatic symptoms, numbers of health care visits in the prior year, and psychological distress; in addition, we hypothesize that sexual maturity is a risk factor for onset of TMD pain and headache; 3) Estimate rates of offset and recurrence of each of the pain c9ompliants over the 3-year follow up period; and, 4) Conduct examinations of the incidence cases of TMD pain, using examination methods and diagnostic algorithms as described for Study 1, to estimate the prevalence of specific subtypes of TMD.